TOKYO - China became the first government to organize a mass evacuation of its citizens from Japan's northeast on Tuesday, while other foreigners left the country following radiation leaks at an earthquake-damaged nuclear power plant.

Austria said it is moving its embassy from Tokyo to Osaka, 250 miles (400 kilometers) away, due to radiation concerns. France recommended that its citizens leave the Japanese capital, while the U.S. government advised Americans to avoid travel to Japan.

China's announcement came as Japan's nuclear crisis took a dramatic turn for the worse following an explosion and a fire at reactors at the Fukushima Dai-ichi complex. Japanese authorities said the fire caused radiation to spew into the air and told people living nearby to stay indoors.

The Chinese Embassy in Tokyo said on its website that it was preparing to send buses to remove its nationals from Miyagi, Fukushima, Ibaraki and Iwate prefectures, the hardest-hit provinces.

The embassy said the evacuation was necessary "due to the seriousness of and uncertainty surrounding the accident at the Fukushima nuclear plant at present."

Chinese diplomats were visiting the area to assist Japanese officials, said a Chinese foreign ministry spokeswoman, Jiang Yu, in Beijing. She gave no other details of the operation.

The number of Chinese affected is unclear, but the Ministry of Commerce in Beijing said it had contacted 22,155 Chinese nationals in the quake-hit areas, while another 261 could not be reached. Many Chinese work in factories in Japan, and the area around Fukushima is home to numerous small manufacturers.

China Southern Airlines said it will use larger, 272-seat aircraft on the route between Tokyo and the Chinese city of Shenyang to handle the evacuees, the official Xinhua News Agency said.

Tokyo, which is about 170 miles (270 kilometers) from the stricken nuclear complex, reported slightly elevated radiation levels, but officials said the increase was too small to threaten the 39 million people in and around the capital.

Liezel Strauss, a South African art consultant in Tokyo, decided to leave Tuesday after her husband and mother called from abroad and said they were very concerned about her.

"Up to this point I was adamant to stay," Strauss, 32, said in an exchange of Twitter messages from her mobile phone as she rushed to the airport for a flight to Singapore. She thought the foreign press was overdramatizing, she added, but "now I'm not so sure anymore. Maybe it was time to get out."

Due to the risk of more earthquakes and uncertainty about the nuclear question, said an e-mail from the French embassy to its citizens, "it seems reasonable to advise that those who have no particular reason to stay in the Tokyo region leave ... for a few days."